// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2012 Désiré Nuentsa-Wakam <desire.nuentsa_wakam@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_SPARSELU_UTILS_H
#define EIGEN_SPARSELU_UTILS_H

namespace Eigen {
namespace internal {

    /**
 * \brief Count Nonzero elements in the factors
 */
    template <typename Scalar, typename StorageIndex> void SparseLUImpl<Scalar, StorageIndex>::countnz(const Index n, Index& nnzL, Index& nnzU, GlobalLU_t& glu)
    {
        nnzL = 0;
        nnzU = (glu.xusub)(n);
        Index nsuper = (glu.supno)(n);
        Index jlen;
        Index i, j, fsupc;
        if (n <= 0)
            return;
        // For each supernode
        for (i = 0; i <= nsuper; i++)
        {
            fsupc = glu.xsup(i);
            jlen = glu.xlsub(fsupc + 1) - glu.xlsub(fsupc);

            for (j = fsupc; j < glu.xsup(i + 1); j++)
            {
                nnzL += jlen;
                nnzU += j - fsupc + 1;
                jlen--;
            }
        }
    }

    /**
 * \brief Fix up the data storage lsub for L-subscripts. 
 * 
 * It removes the subscripts sets for structural pruning, 
 * and applies permutation to the remaining subscripts
 * 
 */
    template <typename Scalar, typename StorageIndex> void SparseLUImpl<Scalar, StorageIndex>::fixupL(const Index n, const IndexVector& perm_r, GlobalLU_t& glu)
    {
        Index fsupc, i, j, k, jstart;

        StorageIndex nextl = 0;
        Index nsuper = (glu.supno)(n);

        // For each supernode
        for (i = 0; i <= nsuper; i++)
        {
            fsupc = glu.xsup(i);
            jstart = glu.xlsub(fsupc);
            glu.xlsub(fsupc) = nextl;
            for (j = jstart; j < glu.xlsub(fsupc + 1); j++)
            {
                glu.lsub(nextl) = perm_r(glu.lsub(j));  // Now indexed into P*A
                nextl++;
            }
            for (k = fsupc + 1; k < glu.xsup(i + 1); k++) glu.xlsub(k) = nextl;  // other columns in supernode i
        }

        glu.xlsub(n) = nextl;
    }

}  // end namespace internal

}  // end namespace Eigen
#endif  // EIGEN_SPARSELU_UTILS_H
